Hi,

I seam to have created 2 threads covering this topic, so apologies for that, I just wanted the title to reflect the content to aid anyone searching in the future.

Thanks all for the ideas generated, they are all welcome.

I will probably retest with an elastic band on the valve lever, it makes sense and inexpensive (not counting Petrol), so appeals to the Yorkshireman..

I accept that the Bypass was cheap and therefore this was almost inevitable, but it is a replacement part for an Explorer so I thought it should work. The obvious difference is I fitted it without the Vacuum actuator it came with, which backs up the theory of needing some pressure on the valve lever..

I had a really good look at all the pics of the Bypass identified by John, I don't want to stifle any ideas and thanks for bothering to search, but I don't think its a 4 way. To me it looks like the Valve sits at the junction of 3 ports with one going to a T, which makes it very similar to the Taxi one in concept. It's really hard to tell when they don't provide enough detail, not even the ID diameter of the ports.

More sophisticated Bypasses do exist, more in the States such as this one which Gambalunga found.

https://www.thermotion.com/4-port-electronic-heater-control-valve-pn-354-69694

But it also needs a control module, a potentiometer and is a bit OTT for my needs, a simple On/Off valve will suffice. interesting to me was that the basis of it looks very similar to the cheap one I purchased, everything is made in China!

Thanks again.

Mark
2015 +4 Ferrari Le Mans Blue